Cognitive Multi-User Ofdma

1. A system comprising a computing device that includes at least one processor and at least one program module that are together configured for performing actions comprising; determining, by the computing device, a number of sub-channels of a plurality of sub-channels within a particular frequency spectrum that is divided into multiple channels that are each further divided into sub-channels of the plurality of sub-channels, where the determined number of sub-channels are sufficient for transmitting data at a desired data rate; selecting, by the computing device until the determined number of sub-channels is selected without regard to whether the selected sub-channels are contiguous or non-contiguous, ones of the plurality of sub-channels within the particular frequency spectrum, where the selecting avoids any of the plurality of sub-channels that are deemed unsuitable for communication; first transmitting, by the computing device to a second device via a control frequency and a particular protocol, a notification message that identifies the selected ones of the plurality of sub-channels within the particular frequency spectrum; and second transmitting, by the computing device in response to the notification message being transmitted and without requiring any response to the transmitted notification message, the data to the second device via the selected ones of the plurality of sub-channels within the particular frequency spectrum.

2. The system of claim 1 where a sub-channel is deemed unsuitable by determining that the sub-channel is being used by another device.

3. The system of claim 1 where a sub-channel is deemed unsuitable by determining that the sub-channel is being subjected to at least a threshold amount of electronic interference.

4. The system of claim 3 where the determining that the sub-channel is being subjected to at least a threshold amount of electronic interference is based on monitoring the sub-channel.

5. The system of claim 1 , the actions further comprising reporting a data rate supported by the selected ones of the plurality of sub-channels.

6. The system of claim 1 where the transmitted notification message serves to reserve for use the selected ones of the plurality of sub-channels.

7. A method performed by a computing device according to computer-executable instructions, the computing device of a plurality of computing devices, the computing device comprising at least one processor and memory, the method comprising: determining, by the computing device, a number of sub-channels of a plurality of sub-channels within a particular frequency spectrum that is divided into multiple channels that are each further divided into sub-channels of the plurality of sub-channels, where the determined number of sub-channels are sufficient for transmitting data at a desired data rate; selecting, by the computing device until the determined number of sub-channels is selected without regard to whether the selected sub-channels are contiguous or non-contiguous, ones of the plurality of sub-channels within the particular frequency spectrum, where the selecting avoids any of the plurality of sub-channels that are deemed unsuitable for communication; first transmitting, by the computing device to a second device via a control frequency and a particular protocol, a notification message that identifies the selected ones of the plurality of sub-channels within the particular frequency spectrum; and second transmitting, by the computing device in response to the notification message being transmitted and without requiring any response to the transmitted notification message, the data to the second device via the selected ones of the plurality of sub-channels within the particular frequency spectrum.

8. The method of claim 7 where a sub-channel is deemed unsuitable by determining that the sub-channel is being used by another device.

9. The method of claim 7 where a sub-channel is deemed unsuitable by determining that the sub-channel is being subjected to at least a threshold amount of electronic interference.

10. The method of claim 9 where the determining that the sub-channel is being subjected to at least a threshold amount of electronic interference is based on monitoring the sub-channel.

11. The method of claim 7 further comprising reporting a data rate supported by the selected ones of the plurality of sub-channels.

12. The method of claim 7 where the transmitted notification message serves to reserve for use the selected ones of the plurality of sub-channels.

13. At least one hardware computer-readable medium comprising: a computer memory, the at least one computer-readable medium storing computer-executable instructions that, when executed by at least one processor of a computing device of a plurality of computing devices, cause the computing device to perform actions comprising: determining, by the computing device, a number of sub-channels of a plurality of sub-channels within a particular frequency spectrum that is divided into multiple channels that are each further divided into sub-channels of the plurality of sub-channels, where the determined number of sub-channels are sufficient for transmitting data at a desired data rate; selecting, by the computing device until the determined number of sub-channels is selected without regard to whether the selected sub-channels are contiguous or non-contiguous, ones of the plurality of sub-channels within the particular frequency spectrum, where the selecting avoids any of the plurality of sub-channels that are deemed unsuitable for communication; first transmitting, by the computing device to a second device via a control frequency and a particular protocol, a notification message that identifies the selected ones of the plurality of sub-channels within the particular frequency spectrum; and second transmitting, by the computing device in response to the notification message being transmitted and without requiring any response to the transmitted notification message, the data to the second device via the selected ones of the plurality of sub-channels within the particular frequency spectrum.

14. The at least one hardware computer-readable medium of claim 13 where a sub-channel is deemed unsuitable by determining that the sub-channel is being used by another device.

15. The at least one hardware computer-readable medium of claim 13 where a sub-channel is deemed unsuitable by determining that the sub-channel is being subjected to at least a threshold amount of electronic interference.

16. The at least one hardware computer-readable medium of claim 15 where the determining that the sub-channel is being subjected to at least a threshold amount of electronic interference is based on monitoring the sub-channel.

17. The at least one hardware computer-readable medium of claim 13 , the actions further comprising reporting a data rate supported by the selected ones of the plurality of sub-channels.

18. The at least one hardware computer-readable medium of claim 13 where the transmitted notification message serves to reserve for use the selected ones of the plurality of sub-channels.